Apparatus for preparing open sand molds suitable for casting large metal plates

ABSTRACT

Open sand molds suitable for casting large metal plates, especially aluminium plates for building facades are prepared by using a large roller bearing a model and rolling spaced guides to level a bed of moldable substance therebetween and simultaneously impressing the molding pit in the bed.

United States Patent 1191 Arbenz et al.

1 11 3,812,902 [451 May 28, 1974 APPARATUS FORPREPARING OPEN SAND MOLDS SUITABLE FOR CASTING LARGE METAL PLATES [75] Inventors: Heinz Arbenz, Andelfingen; Jakob Caspar, Kaltenbach, both of Switzerland [73] Assignee: Swiss Aluminium Ltd., Chippis,

Switzerland [22] Filed: Nov. 3, 19711 21 Appl. No.2 195,274

[30] Foreign Application Priority Data Nov. 6, 1970 Switzerland 16462/70 [52] US. Cl. 164/208 [51] Int. Cl. B22c 15/02 [58] Field of Search 164/18, 37, 40, 410, 207, 164/208 [56] References Cited UNITED STATES PATENTS 459,102 9/1891 Adams 164/18 865,511 9/1907 Mehaffey 1,072,229 9/1913 l-loose 1,083,546 1/1914 MacDonald 3,628,593 12/1971 Staley 164/208 Primary ExaminerJ. Spencer Overholser Assistant ExaminerJohn E. Roethel Attorney, Agent, or Firm-Emest F. Marmorek [57 ABSTRACT Open sand molds suitable for casting large metal plates, especially aluminium plates for building facades are prepared by using a large roller bearing a model and rolling spaced guides to level a bed of moldable substance therebetween and simultaneously impressing the molding pit in the bed.

7 Claims, 6 Drawing Figures 7 PATENTEBIAYZB 1w 3.5812 902 Y SHEET 3 0F 5 Fig. A

memcnmzsm I 3.812.902 SHEET s (If 5 Fig. 5

APPARATUS FOR PREPARING OPEN SAND MOLDS SUITABLE FOR CASTING LARGE METAL PLATES The stove casting process is a very old one. Under this process one understands an open cast in a sand bed in which the molding cavity is hollowed out and no mold top part is used. This process is only admissible when one side in this case the top side of the casting is plane. Cast iron cooking stove plates were produced in this manner more than a century ago.

in recent years, stove casting (also called open sand casting and hereinafter as such referred) has found its way into a new sphere of applications, i.e., for the casting of plane plates made from aluminium for building facades. Such plates are not only exceptionally resistant to weather conditions, but, because of their very attractive and characteristic surface structures (cast striae, colored oxide accumulations, hammered effects, macro-crystals, craters and bubbles), have a popular architectonic effect. These. effects are advantageous inasmuch as the surfaces, which are solidified in free air without being in contact with the sand mold may be used as apparent and exposed surfaces.

The following processes are known for the production of such plates:

a. ln a molding box requiring inversion: The model, a smooth plate having a prescribed wall thickness and usually provided with edges and ribs, is lain on to the mold or the Casting Plant floor; themolding box is placed over it and casting sand (green molding sand) is filled up and stamped. The molding box is then inverted and the model lifted out. When casting in the pit left by the model in the molding sand it is important that the entire mold lies absolutely horizontal. The metal must be distributed by means of an adequate number of casting ladles, according to size, in order to produce thin, cold shotfree plates.

b. impressing the plate model in a plane sand bed: The mold boxes, or a frame standing ready on the casting plant floor are filled with sand and then brought to a light compactness by either a light stamping or by rolling. The model is then placed on to the plane sand surface with the ribbed side facing downwards and pressed hard so far into the sand so that a mold cavity of the desired depth and corresponding to the plate thicknesses is obtained.

Here it is usually necessary to line the edge of the sand between the plate model and bed lining or casting box with an additional small quantity of sand and to even if off by scraping.

The model can be pressed in by loading it with weights or by means of a hydraulic cylinder. it is how ever necessary to load thin models uniformly with a ribbed construction made from wood or metal.

Pressure to be applied must be approx. 1,000 kp/m These processes incur much manual work because they are discontinual and it is often necessary to repair the edges.

An object of the present invention is to considerably reduce this manual work by using a process which can be carried out in either half or full continuity.

The present invention refers to a process for the continual production of the above mold casting pits which are open at the top (open cast molds) for the production of plate-shaped metal casts, by molding a model in a bed filled with a moldable substance, in which one presses the entire open cast mold into a bed filled with a moldable substance by means of a mechanically driven stamping roller revolving on its own axis and by means of at least one model piece brought on to the roller.

One can proceed to advantage by rolling the loosely piled casting sand into a long sand bed situated between two parallel rails, thereby simultaneously levelling off and pressing the molding pit into the desired dimensions by a single operation. The stamping of the plate molds is efiected by a continuous rolling procedure which can'be carried out at high speed (for example, approx. 0.2 m/sec.)

When carrying out the process according to the invention the greatest variety of natural and/or synthetic materials available to one skilled in the art, such as sands like quartz, zircon silicate or of ceramic products, also with additions of binding agents, for example natural clay or betonite, hardening agents, plastify- .ing agents, oxidation'preventing agents and further,

heat dissipation regulators such as chill plates or thermal insulators can be used as moldable substances or accessories for the stamping of the mold.

To produce casts of low gas content, binding agents (for example made from organic material) which are either anhydrous or of low humidity can for example be used forthe preparation of moldable substances to be applied.

Neither is there anything to prevent the use of the known physical aids such as heat conduction or oscillation energies, whether on the molding substance itself or on an applied stamping roller according to the invention; nor the use of easily separable, or counteracting chemical insulating dustings or powderings on mold or cast parts after casting.

Generally, the process of the invention permits the production of molds usable for plates and also apparatus parts and the like made from all metals and alloys suitable for mold casting, including heavy and light metals, especially for the production of plates from aluminium and its alloys for the construction of facades.

Depending on the diameter of the stamping roller and the composition of the' mold substance, the roller should exercise a pressure on the mold bed corresponding to the purpose for'which it is required. According to the invention the weight of the stamping roller can be increased, for example by filling with sand, water or the like, or one can, for example, increase the pressure of the roller on the moldable substance by such known means as, for example, hydraulic pressure or mechanical pressure such as of springs or screws.

According to a method of carrying out the process of the invention one slips a model-carrying tube on to the roller and thus stamps the open cast mold. This is favourable because one can change the model relatively quickly between two stamping operations.

One method of carrying out the process according to the invention is: that the roller, rotating on its own axis' ler revolving around its own longitudinal axis (but otherwise stationary) and stamps the open cast mold by means of the revolving roller into the bed.

Hereby individual mold boxes containing the filled bed may be led under the revolving stamping roller, thus stamping the open cast mold into the bed by the pressure of the weight of the roller. Furthermore, if desired, a continual assembly line or a continual endless line can be formed by leading the bed under the roller, thus permitting many or numerous open cast molds to be continually and successively stamped by means of the stamping roller and then filled with molten metal.

From the aforesaid it is apparent that by means of the process according to the invention one can in fact achieve a fully continuaL time and space-saving assembly line product whereby, with specified aids known to plant and fixed, thus forming degassing slits below the rails for the escape of the casting gases (see items in FIG. 1 and 20 which are explained below).

According to an advantageous method of the process according to the present invention, the stamping roller is moved in a rolling manner on rails along the filled mold bed and stamps the open cast mold into the mod bed by means of the pressure of the roller.

The present invention also refers to devices for carrying out the above described process.

- One such device has a mechanically driven stamping roller for stamping the open cast mold, said roller being provided with 'at least one stamp to produce a suitable model in a moldable substance.

Advantageously, the device can for example be so constructed that the mechanically driven stamping roller is a part of a mobile conveyor guided on or between rails and moved relatively to the mold bed and that the device has means such as rolls or chains to pilot the conveyor and to prevent it lifting ofi.

F lGS. l 6 illustrate schematically an example of the method of the process according to the invention in which the stamping roller rolls on rails above the filled bed and the open cast mold is stamped into the bed by the pressure of the stamping roller.

FIG. 1 is a side view drawn partly in section of a device for carrying out that method.

FIG. 2 illustrates a vertical cross section of the rolling procedure of a stamping roller.

FlG. 3 illustrates a longitudinal and also frontal view (right) of a strickle which serves to level and prepare a sandbed prior to the stamping procedure.

FIG. 4 illustrates a longitudinal, as well as a frontal view (right) of a separator which, inserted in a produced open cast mold, separates the individual cast 4 metal plates from each other during the metal melt into the open cast mold.

FlG. 5 illustrates part of a cross-section through a stamping roller to be applied according to the invention casting of on which a flexible model is bent upwards and secured.

FIG. 6 illustrates avertical longitudinal cross section parallel to the rolling direction of-the stamping roller of an already formed and prepared mold bed for castin a metal melt according to the invention.

Above the floor of the Casting Plant are rails l serving as cast bed limits (FIG. 1). The stamping roller 2 rolls on these rails and is guided by the ring gibs 3.

To press the molding pit into the molding sand the stamping roller 2 carries, with very little play, a first pattern such as a tube 4 (as part of the model) which has about the same thickness as the plate to be cast. The tube 4 is limited left and right by two rings 5 which serve to stamp the edges of the plates. The width of the plates can be changed as desired by varying the length of the tube 4. The rings 5 can be exchanged to alter the shape and height of the plate edges.

The rings 5 and the ring gibs 3 are secured to the stamping roller by means of screws.

The length of the individual plate molds to be produced is primarily dependent on the diameter of the stamping roller. The tube 4 may be provided with a slit so wide that the circumference of the tube corresponds to approximately the length of the plates; model parts are then placed on the edges of the slit parallel to the rolling axis, which parts serve to stamp the plate edges which are parallel to the rolling axis.

Since the stamping roller 2 and the accessory parts 5, 4 and 3 are relatively costly, one will endeavour to handle various plate lengths with only one device. This being so, the tube 4 can be left without cross slit, thereby rendering its entire circumference usable. To make this possible one can, for example, screw another pattern such as a gib 6 on to the tube 4, which gib serves to prepare the area of the edges on both the ends of the plates to be cast. The width of the gib 6 then corresponds to the circumference of the tube, minus plate lengths, plus twice the edge width.

In determining all these dimensions, in view of the plate to be produced, the shrinkage of the casting metal must be taken into consideration. In the case of aluminium alloys shrinkage is usually l.2 percent.

The moldable substance, e.g., molding sand in the present example, is piled loosely and as evenly as possible from a mobile silo in order to make a mold bed. To facilitate the roll stamping a molding strickle, illustrated in FIG. 3, is drawn above the surface of the moldable substance, being glided on the rails l and thereby guided ,by, the corner pieces 8 fixed on the lower side of the strickle 7 thus effecting an approximately equal distribution of the sand on the surface and, due to the cut-outs on the lower side of the strickle 7, an accumulation of sand on those places where the roller would effect a relatively low compactness. This mainly refers to the areas between the longitudinal plate edges 5 and the rails l (FIG. 1). Alternatively, it is possible to add at such areas a mound of sand reaching above the level of the rails, thus permitting an even, overall compactness of the sand by the subsequent stamping with the roller.

The stamping procedure and the periodical mold stamping of the gib 6 into the mold bed 9 is illustrated in FIG. 2. In order to form separate plates when casting the separator is put into the distance corresponding to the required plate lengths in the pit formed by pressing the gib 6 into the mold bed 9 (H68. 4, 6). The recesses 11 on the ends of the separator 10 (FIG. 4) serve to act as supports on the rails 1. Each pair of separators 10 are always bracketed together by means of spacers 12, or secured together, thus giving the distance b between the individual plates. It is suitable to construct and use the separators so that they lie well on the rails 1 and fit exactly in the mold pit.

Instead of separators l0, separation between plates can be effected by other means, for example by sand walls, or can be molded directly by corresponding shape of the stamping model on the roller.

Another possibility of realizing the model piece is, that instead of using a steel tube slipped on the roller, one casts the model piece 4 as a plate made from a flexible metal, for example soft lead, together with the necessary edges, bending said plate up on the stamping roller 2 and then securing it by means of, for example, screws, nuts or other means. Analogously, a plastic plate can be produced which one accordingly applies by bending after being previously warmed. Similarly, single or multilayered rubber plates 14 of the same thickness as the open cast plates may be utilized, said rubber plates being bent around the stamping roller 2 and (FIG. 5) fixed by the gibs 6 which are screwed on to the roller.

ln this case the gibs 6 are provided with sharp, slightly protruding edges for the purpose of ensuring a secure fixing of the rubber plates 14. This permits a slight stretching of the plates and prevents them from slipping during rolling. If necessary an adhesive can be applied between the rubber plates 14 and the metal stamping roller 2. The roller should not, of course, cant when being rolled on the rails 1, Le, the axis must always lie perpendicular to the direction of the rails. In order to ensure correct rolling on the rolling surface 16 of the stamping roller 2 equally distanced cogs 17 are provided which grip in the holes 18 in the rails l and serve to guide the stamping roller 2. Instead of this and to achieve the same effect, one can provide each end of the stamping roller 2 with a toothed rim which grips in tooth racks or in the links of suspended chains which can be connected to the rails H. The space provided between the rails l and the Casting Plant floor 19 serves as a degassing vent.

What is claimed is:

l. A device for the production of an open mold casting pit for casting metallic plates having at least a pair of parallel sides,

comprising, in combination, a roller driven for rotation about its own axis and car- 5 rying at least one pattern fixed to a central surface portion thereof,

spaced guide means arranged in a horizontal plane for supporting lateral surface portions of the roller and operable for receiving a bed of moldable substance therebetween,

the roller and the guide means being movable relative to each other,

said pattern including at least a pair of lateral rings axially mounted on the roller at a distance from said guide means and a substantially cylindrically curved plate secured on the roller between the rings, the outer diameter of the rings being greater than the outer diameter of the plate.

2. A device for the production of an open mold cast- 20 ing pit, for use in casting longitudinal plates,

comprising, in combination,

a pair of guides having upper surfaces arranged in a horizontal plane and defining therebetween a mold space for receiving a moldable substance,

a stamping roller operable to be in rolling contact with said upper surfaces of the guides,

at least one curved pattern secured to said roller above said mold space adapted to impress a continuous pattern into said moldable substance, and

a gib extending axially of said roller throughout the width of the curved pattern thereby being adapted to make impressions in said moldable substance throughout the pattern width thereof to separate adjoining pit patterns.

3. A device according to claim 1 further comprising at least one gib bridging said rings to separate adjoining pits.

4. Device according to claim 2 in which synchronisation means are provided to prevent a slippage in the relative movement between roller and mold bed.

5. Device according to claim 2 in which said guides include parallel rails and means for guiding the roller in a straight direction.

6. Device according to claim 1 in which the pattern consists of a closed cylinder slipped on the roller and supporting a gib disposed parallel to the roller axis.

7. Device according to claim 5 in which the pattern on the stamping roller includes a pair of separate lateral rings. 

1. A device for the production of an open mold casting pit for casting metallic plates having at least a pair of parallel sides, comprising, in combination, a roller driven for rotation about its own axis and carrying at least one pattern fixed to a central surface portion thereof, spaced guide means arranged in a horizontal plane for supporting lateral surface portions of the roller and operable for receiving a bed of moldable substance therebetween, the roller and the guide means being movable relative to each other, said pattern including at least a pair of lateral rings axially mounted on the roller at a distance from said guide means and a substantially cylindrically curved plate secured on the roller between the rings, the outer diameter of the rings being greater than the outer diameter of the plate.
 2. A device for the production of an open mold casting pit, for use in casting longitudinal plates, comprising, in combination, a pair of guides having upper surfaces arranged in a horizontal plane and defining therebetween a mold space for receiving a moldable substance, a stamping roller operable to be in rolling contact with said upper surfaces of the guides, at least one curved pattern secured to said roller above said mold space adapted to impress a continuous pattern into said moldable substance, and a gib extending axially of said roller throughout the width of the curved pattern thereby being adapted to make impressions in said moldable substance throughout the pattern width thereof to separate adjoining pit patterns.
 3. A device according to claim 1 further comprising at least one gib bridging said rings to separate adjoining pits.
 4. Device according to claim 2 in which synchronisation means are provided to prevent a slippage in the relative movement between roller and mold bed.
 5. Device according to claim 2 in which said guides include parallel rails and means for guiding the roller in a straight direction.
 6. Device according to claim 1 in which the pattern consists of a closed cylinder slipped on the roller and supporting a gib disposed parallel to the roller axis.
 7. Device according to claim 5 in which the pattern on the stamping roller includes a pair of separate lateral rings. 